Aitken's Nucleus Counter. Instrument for counting number of hygroscopic particles in a given volume of air, which is cooled adiabatically by expansion. Water droplets, each containing a nucleus, are deposited; these are counted with aid of a microscope.
Aker. Name given to a tidal bore sometimes met with in estuaries. Cognate with 'Eagre', 'Acker'.
Al. Arabic word meaning 'The'.
Alba.* Old name for a lighthouse or beacon.
Albacore. Small edible fish of mackerel family. Found near West Indies and in Pacific Ocean.
Albedo. Light reflecting power of Moon, planet or satellite. Value is expressed as a fraction that denotes proportion of light that is reflected. Term may be used in connection with radiations other than light.
Albert Medal. Established by Queen Victoria, in 1866, and awarded for saving life at sea. Later, extended to include saving life on land. Ribbon is blue for sea medals, red for land medals.
Albiero. Star Cygni. S.H.A. 68°; Dec. N 28°; Mag. 3-2.
Alcor. Name of a small star close to Mizar in Ursa Major. Is often called 'the rider' (of one of the horses of Charles' Wain), or 'the Tester' (of eyesight).
Alcyone. Star Tauri. S.H.A. 304°; Dec. N 24°; Mag. 3-0. Name is Greek for 'Kingfisher'. At one time was thought to be the central star of the Universe.
Aldebaran. Star Tauri. a R.A. 04h 33m; Dec. N 16°; Mag. 1-1. S.H.A. 292°. Diameter is 60 times that of Sun; distant 57 light years; temperature 3300°A. Is one of the Hyades. Name is Arabic for 'Eye of the Bull'.
Alderamin. Star Cephei. S.H.A. 41°; Dec. N 62°; Mag. 2-6.
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